Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services now if the exposed person:
It is also appropriate to seek confidential support for repeated or intentional inhalant use, even when there are no current emergency symptoms.
And for anyone, someone who:
Contact a poison centre promptly after swallowing hair spray, a large inhalation exposure, or any exposure involving symptoms.
In the United States, Poison Control is available at 1-800-222-1222 and through webPOISONCONTROL.
Elsewhere, use your national poison-information service or urgent medical service.
Arrange urgent medical assessment for a cough that worsens after swallowing, fever, shortness of breath, chest pain, repeated vomiting, ongoing drowsiness, or persistent blurred vision or eye pain.
Routine follow-up is appropriate if mild symptoms are not settling as expected, workplace exposure keeps causing irritation, or you have been advised to have your lungs, heart, or eyes rechecked.
The article also says
Move away from fumes if it is safe, but do not put yourself at risk.
Do not give food or drink to someone who is unconscious or having difficulty swallowing.
Every sign above is quoted from the sofidex article on Hair spray poisoning. If you are not sure, err upward — it is always reasonable to be checked.